Pressure indicating device



-2 1965 R. BECCIANI ETAL 3,

PRESSURE INDICATING DEVICE Filed May 51, 1963 1 5 a A 9 34 5 33 1a 7.

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I (igent United States Patent 3,224,264 PRESSURE INDICATING DEVICE Renato Becciani, Via Magnasco 2, Milan, Italy, and Luigi Valtorta, Via Podgora 110, Sesto San Giovanni, Milan,

The present invention relates to a pressure indicating device, which is particularly adapted to be attached directly to tire valves of vehicles in general, and serve also as a closing cap of such valves.

An object of the present invention is to provide a pressure indicating device of the described kind, which will be reliable in operation, of simple but durable construction and of low cost.

Further objects and advantages of the invention will be more evident from the description which follows of two preferred but not exclusive embodiments of the invention illustrated in the accompanying drawing in which:

FIG. 1 is a sectional view according to the longitudinal axis of the first embodiment of the pressure indicator.

FIG. 2 is a perspective View of the pressure indicator shown in FIG. 1.

FIG. 3 is a perspective view of a bell shaped indicating member, and

FIG. 4 is a sectional view similar to that of FIG. 1 of a second embodiment of the pressure indicator.

Referring to the figures, in which like reference nu merals designate like or corresponding parts, it will be seen that the pressure indicator is formed of an outer hollow body 1, the upper substantially ovoidal portion 2 of which has externally a knurling 3, while the lower cylindrical portion 4 is provided along a length of its outer surface 5 with spaced substantially rectangular windows 6 providing a communication between the cavity of said hollow body 1 and the outside. The annular portion provided with the windows 6 is covered by a ring 8 of transparent material, e.g. of plastic material commercially known under the name of Plexiglas, so that through said windows 6 a substantially bell shaped hollow cylindrical element 9 may be completely seen, said element being slidably mounted in the cavity 7 of body 1 and in contact with the inner surface of said cavity through its ends 10 and 11 provided for the purpose with edges 10a and 11a.

An elastic diaphragm or bellows member -12, mounted inside said cylindrical element 9, may be deformed by the pressure to be measured and this deformation defines the movement of said bell shaped cylindrical element 9. The elastic diaphragm 12, of flexible and defor-mable material is oversized so that it assumes the form of a bag the neck of which is fixed on the inner flange-like upper portion 13 of a sleeve member or cylindrical wall 14, the lower portion of which is outwardly bent to form an annular boss 15 integral therewith and slipped in an air tight manner over and fixed on the lower portion 4 of body 1. The boss part 15 extends up to the lower end 16 of the annular zone provided with the windows 6. Internally the sleeve member is provided with a screw thread 17 adapted to be screwed on the tire valve (not shown in the drawing). In order to fix securely the elastic diaphragm 12 said inner flangelike upper portion 13 of the sleeve member 14 is bent inwardly to form an inner flange portion provided on the lower surface thereof, with an annular groove 18 in which there is pressed the deformable material of said elastic diaphragm 12 wound around the inner flange portion 13. Owing to the inner flange-like upper portion 13 the end portion of the diaphragm 12 forms an abutment 19 onto which the disc 20 is pressed, such disc being provided with a small hole 21 adapted to allow communication between the chamber 22, defined by the elastic diaphragm 12, and the interior 23 of the sleeve member 14. The plate-like top wall 24 of the chamber 22 of the elastic diaphragm 12 has a central recess 25 facilitating an air tight closure of the upper end 13 of the sleeve member 14, when wall 24 is lowered. The movement of the cylindrical element 9, caused by the deformation in the expansion direction of said elastic diaphragm 12, is counteracted by the spring 26 located in the recess 27 provided in the portion 2 coaxial with the cavity 7 of the body 1 and acting against the upper external surface 10b of said cylindrical element 9. The cylindrical element 9 has on its lateral external surface between the ends 10b and 11a markings or scales 9a for indicating the internal pressure of the tire.

The cavity 7 and recess 27 will communicate with the atmosphere through e.g. one or more little holes (not shown) provided in the body 1. For this purpose the cylinder member 9 may have longitudinal grooves on the outer surface thereof or a clearance may be provided between the walls of cavity 7 and cylinder 9.

The operation is as follows: screwing the thread 17 of the sleeve member 13 of the pressure indicating device on a tire valve stem, disc 20 is brought into contact with the core of said valve, which is consequently lowered thereby opening the tire valve. The air from the tire thus passes through the hole 21, and enters the cavity 22 of the elastic diaphragm 12, which is consequently expanded. Such expansion, counteracted by the calibrated spring 26, causes the raising of the cylindrical element 9. In a given position the counteraction of the spring will balance the pressure action and such position will indicate the internal pressure of the tire. For this purpose, as mentioned, the outer surface of cylinder 9, visible through the windows 6, is provided with pressure condition indicating markings. Preferably'the lower portion of cylinder 9 will bear on its outer surface a marking indicating the optimum value of pressure, while the upper portion will bear a marking indicating the wrong pressure. Such markings will preferably have, respectively, a suitable distinguishing colouring e.g. the marking for normal pressure will have the same colouring of the external shell and that for the wrong pressure will have a red 'colour.

In case of leakages due, for instance, to damages of the elastic diaphragm lZ, thepressure will drop to a pre-determined minimum value, without having a complete deflating of the tire as generally happens with known devices of this type. In fact, in the case of leakage due to bursting, when the air pressure within the tire has reached a value which is lower than that exerted by the spring, such spring will press the top wall 24 of the chamber 22, defined by the elastic diaphragm 12, against the end 13 of the sleeve member closing the corresponding opening and preventing further escape of air. In this case the sealing is determined by the central recess 25 provided in the top wall 24.

In fact such recess 25 is provided in order to increase the surface exposed to the pressure of the tire and consequently the lifting force acting on the top wall 24 when the latter is in contact with the end 13 of the sleeve member in opposition to the elastic action of the spring 26.

In the embodiment according to FIG. 4 the sleeve portion 14 is adapted to receive in a stable and fluid tight manner a metallic bush 14a having an inner thread 17 to be screwed on the tire valve. Furthermore, against the 3 annular abutment 19 defined by the end of the diaphragm 12 and the inner flange 13 of the bush 14a, a flange 28a. of a bush member 28 forced in an air tight manner into the aperture 12a of the flexible diaphragm 12 is pressed, said bush member 28 being provided with an axial hole 28!) providing communication 22 between chamber 22 and the inside 23 of the bush 14a. Between the inner surface of said bush 14a and the outer surface of the bush member 28 an annular gasket element 20a is arranged to accomplish a sealing contact between the tire valve stem and the bush member 28, the lower surface of said annular gasket 20a lying in a plane which is parallel and axially downwardly projecting with respect to the lower end surface of said bush member 28.

The communication between cavities 7 and 27 and the outside atmosphere may be provided in a similar manner as described with reference to the embodiment of FIGS. 1-3.

The operation of this second embodiment of the pressure gauge is substantially as above disclosed with reference to the first embodiment. The only difierence consists in the fact that by screwing the outer hollow body 1 through the thread 17 of the bush 14 on a tire valve terminal, firstly the annular gasket element 20a contacts the annular end edge of the tire valve stem so that a fluid tight contact is achieved and subsequently by further screwing the bush member 28a compresses the gasket 20a and presses down the core of the tire valve causing escape of compressed air from the tire within the chamber 22 of the flexible diaphragm 12.

Other features of this embodiment correspond to those previously described.

It will be understood that the foregoing description of the invention and the embodiments shown are merely illustrative of the principles thereof; and, accordingly, that the appended claims are to be construed as defining the invention within the full spirit and scope thereof.

We claim:

1. A pressure indicating device, comprising a hollow body having a closed top part and a bottom part, an opening in said bottom part, a substantially cylindrical wall on said bottom part and surrounding said opening, said cylindrical wall having a diameter smaller than the diameter of the cavity of said hollow body, said cylindrical wall projecting from said bottom within the cavity of said hollow body, at a distance from the top part thereof, a bag-like bellows member of flexible material and having a neck portion of reduced diameter projecting from the body portion of said bellows member having a diameter substantially greater than the diameter of said neck portion, said neck portion fitting within the interior of the top portion of said cylindrical wall, means for fixing said neck portion to the inside of the top portion of said cylindrical wall, a bell member above said cylindrical wall and riding on said bellows member, said bell member being movable within the interior of said hollow body, spring means biasing said bell member towards said cylindrical wall, indication markings on the outer surface of said bell member and window means on the outer wall of said hollow body for allowing vision of said indication marklngs.

2. A pressure indicating device, comprising a hollow body having a closed top part and a bottom part, means defining an opening in said bottom part, a substantially cylindrical wall on said bottom part and surrounding said opening, said cylindrical wall having a diameter smaller than the diameter of the cavity of said hollow body, said cylindrical wall projecting from said bottom within the cavity of said hollow body at a distance from the top part thereof, a bag-like bellows member of flexible material and having a neck portion of reduced diameter projecting from the body portion of said bellows member having a diameter substantially greater than the diameter of said neck portion, said neck portion fitting within the interior of the top portion of said cylindrical wall, means for fixing said neck portion to the inside of the top portion of said cylindrical wall, a bell member above said cylindrical wall and riding on said bellows member, said bell member being movable within the interior of said hollow body, a portion of said bag-like bellows member near the neck portion thereof riding on the top portion of said cylindrical wall and extending therefrom towards the inner surface of said bell member, said bellows member having a plate-like top part opposite to said neck portion thereof and a recess in said plate-like top part facing said neck portion, the diameter of said recess being greater than the inner diameter of said cylindrical wall and smaller than the outside diameter of said cylindrical wall plus twice the thickness of the bellows member portion riding on the top portion of said cylindrical wall, spring means biasing said bell member towards said cylindrical wall, indication markings on the outer surface of said bell member, and window means on the outer wall of said hollow body for allowing vision of said indication markings.

References Cited by the Examiner UNITED STATES PATENTS 1,494,001 5/1924 McPherson 73-146.8 1,633,145 6/1927 Wahl et a1. 73409 1,807,752 6/1931 Poster 73-146.8 1,946,224 2/ 1934 Mastrangel 73-409 X 2,225,675 12/1940 West 73146.8 X 2,704,045 3/ 1955 Riesing 11634 2,948,256 8/1960 Tapp 73-146.8 X

RICHARD C. QUEISSER, Primary Examiner. JOSEPH P. STRIZAK, Examiner. 

1. A PRESSURE INDICATING DEVICE, COMPRISING A HOLLOW BODY HAVING A CLOSED TOP PART AND A BOTTOM PART, AN OPENING IN SAID BOTTOM PART, A SUBSTANTIALLY CYLINDRICAL WALL ON SAID BOTTOM PART AND SURROUNDING SAID OPENING, SAID CYLINDRICAL WALL HAVING A DIAMETER SMALLER THAN THE DIAMETER OF THE CAVITY OF SAID HOLLOW BODY, SAID CYLINDRICAL WALL PROJECTING ROM SAID BOTTOM WITHIN THE CAVITY OF SAID HOLLOW BODY, AT A DISTANCE FROM THE TOP PART THEREOF, A BAG-LIKE BELLOWS MEMBER OF FLEXIBLE MATERIAL AND HAVING A NECK PORTION OF REDUCED DIAMETER PROJECTING FROM THE BODY PORTION OF SAID BELLOWS MEMBER HAVING A DIAMETER SUBSTANTIALLY GREATER THAN THE DIAMETER OF SAID NECK PORTION, SAID NECK PORTION FITTING WITHIN THE INTERIOR OF THE TOP PORTION OF SAID CYLIDRICAL WALL, MEANS FOR FIXING SAID NECK 